I prefer writing in third person, simply because I find it a lot easier. I think that second person requires a more immersive style with the ability to give the protagonist some credible emotions, and not to mention good accounts about the surrounding world within the POV. Since English isn't my first language I often feel that I'm not skilled enough to pull it off. My simple cartoony characters just come out weird(er) in 2nd person.
I'm actually going to kind of be a dick here and say "First". I like feeling as if I am listening to someone telling a story by the campfire, describing their sexual escapades for my entertainment. If I had to pick one of the two choices ordered in this thread though it would be second though. I feel it lends itself quite well to the CH.Y.O.A. Concept, and makes it easier for me to decide: "None of these things are what I actually would do... Time to start writing my own branch for this Story..."
I only have one story here but second person for me to write in is very easy to do. - I want to experience the things i write about - I want to be as descriptive as possible - I want the reader to feel as though this is happening to them. When i think about it a bit, first person is best for a bit of narration in my other (non chyoa) stories when mixed with third person aspect.